Method and apparatus for controlling hydraulic drifters

ABSTRACT

Disclosed herein is a hydraulic circuit for use in conjunction with a hydraulic drifter or impact mechanism used for drilling holes in connection with mining or the like. The hydraulic circuit described is arranged to provide for the rotation of the drill, to supply hydraulic fluid to the drifter for causing reciprocation of the bit, and to supply hydraulic fluid to a feed mechanism to maintain the drifter in engagement with the formation to be drilled. The circuit is arranged to provide for the automatic diversion of a portion of the feed mechanism fluid supply when the pressure in the feed mechanism exceeds a predetermined value. The diverted fluid is supplied to the impact mechanism to provide additional power when the feed mechanism is at or near the stall condition.

United States Patent 1191 Feucht July 16, 1974 METHOD AND APPARATUS FOR CONTROLLING HYDRAULIC DRlFTERS [75] inventor: Jacob Edward Feucht, Sidney, Ohio [73] Assignee: Dresser Industries, Inc., Dallas, Tex. [22] Filed: June 8, 1973 [2]] Appl. No.: 368,152

Primary Examiner-David H. Brown Attorney, Agent, or FirmRoy L. Van Winkle [57] ABSTRACT Disclosed herein is a hydraulic circuit for use in conjunction with a hydraulic drifter or impact mechanism used for drilling holes in connection with mining or the like. The hydraulic circuit-described is arranged to provide for the rotation of the drill, to supply hydraulic fluid to the drifter for causing reciprocation of the bit, and to supply hydraulic fluid to a feed mechanism .to maintain the drifter in engagement with the formation to be drilled. The circuit is arranged to provide for the automatic diversion of a portion of the feed mechanism fluid supply when the pressure in the feed mechanism exceeds a predetermined value. The diverted fluid is supplied to the impact mechanism to provide additional power when the feed mechanism is at or near the stall condition.

9 Claims, 1 Drawing Figure ROTATION VALVE at 30C) ROTATION PUMP T FEED MOTOR PRESSURE REDUCER IMPACT I VALVE 4o 24 E 3 UP 64 112mg;

KN g m Dee 50 p E OWN ff 0 o 2 I 52 m 1 E FEED 515B \L VALVE BACKGROUND OF THE INVENTION This invention relates generally to hydraulically actuated percussion drills or, as they are known in the art, hydraulic drifters. More particularly, but not by-way of limitation, this invention relates to an improved control circuit for use with such drills that is arranged to provide the maximum fluid power to the impact mechanism when the drill is being used in formations that are extremely difficult to drill.

In the past, it has been known to provide an independent means for rotating the drill bit during drilling to promote even drilling and to promote even wear on the drill bit. It has also been known to provide a separate power source for causing reciprocation of the impact mechanism. One example of a hydraulic drifter may be found in US. Pat. No. 3,701,386, issued Oct. 31, 1972 to Jacob E. Feucht. That patent fully describes the structure and operation of the impact mechanism shown schematically herein.

In addition to the foregoing, a separate power supply source has been provided for driving the feed mechanism which moves the impact mechanism and the bit toward the formation to be drilled and applies a continual force thereto so that the drill will drill more rapidly. The same source of fluid supply is also used to move the impact mechanism relatively away from the formation for the purpose of changing drill bits, adding or removing drill steels, etc.

During such drilling operations, and particularly when formations that are very difficult to drill are encountered, the feed mechanism will exert a force .on the impact mechanism. When the feed mechanism approaches or reaches'the stall condition, a relief valve is provided so that the pressure in the hydraulic feed circuit will not exceed some predeterminedvalue. Normally the pressure will exceed the predetermined value when the stall condition is approached and fluid will be circulated back to the hydraulic reservoir. The constant displacement pump utilized in such circuits is then operating very inefficiently because considerable fluid is simply being circulated through the circuit without doing any additional work.

are such that full flow conditions are required to both mechanisms.

SUMMARY OF THE INVENTION In one aspect, this invention provides an improved hydraulic circuit for controlling the feed force and impact force exerted by a hydraulic drifter that includes an impact mechanism including a hydraulically actuated reciprocating piston causing the impact force and a feed mechanism powered by hydraulic motor for moving the impact mechanism toward and away from the formation being drilled, the improvement comprising: first means for supplying pressure fluid to the impact mechanism; second means for supplying pressure fluid to the feed mechanism; and, third means interconnecting the first and second means for fluid communication, the third means including normally-closed valve means, presettable to open in response to a predetermined pressure in the second means permitting fluid flow from the second means to the first means when the pressure in the second 'means exceeds the predetermined pressure, whereby the impact mechanism receives fluid under pressure from the feed mechanism.

In another aspect of the invention, there is contemplated a method for automatically controlling the application of hydraulic power between the impact force and feed force in a hydraulic drifter that includes an impact mechanism having a hydraulically actuated reciprocating piston for causing the impact force, the impact pump for supplying hydraulic fluid to the impact mechanism, a feed mechanism powered by a hydraulic motor for'moving the impact mechanism toward and away from the formation being drilled, a feed pump for supplying hydraulic fluid to the feed mechanism, and pressure-responsive valve means operably disposed between said impact mechanism and feed mechanism, the method comprising the steps of: supplying fluid under pressure to cause reciprocation of the piston in the impact mechanism by means of an impact pump; supplying fluid to the feed mechanism to force the impact mechanism into engagement with the formation by means of a feed pump; and, opening the valve means One object of this invention is to provide .an improved hydraulic circuit for powering hydraulic drifters that will utilize the excess pressure built up by the pump in the feed mechanism to impart additional power to the impact mechanism.

Another object of the invention is to provide an improved hydraulic circuit wherein the control circuit automatically prevents the diversion of fluid in the event that a relatively easy formation to drill is encountered.

- an improved control circuit for hydraulic drifters wherein both full flow to the impact mechanism and full flow to the feed mechanism is available when the formation encountered or the conditions of operation lowing detailed description is read in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE of the drawing is a schematic illustration of a hydraulic circuit constructed in accordance with the invention and utilized to control a hydraulic drifter.

DETAILED DESCRIPTION THE PREFERRED EMBODIMENT The single FIGURE of the drawing schematically illustrates a hydraulic drifterlO and the hydraulic power circuit associated therewith. The hydraulic drifter 10 includes an impact mechanism 12 having a housing 14 which encompasses a reciprocating piston or striker 16.

The housing14' is appropriately arranged with ports 3 and passageways to cause reciprocation of the piston or striker 16. A shank bar 18 extends from the housing 14. One end of the shank bar 18 is arranged to be impacted by the piston 16 and the other end thereof is adapted to be connected with a drill steel 20 that is connected at its lower end to a drill bit 22. It will, of course, be understood that a plurality of the drill steels 20 may be utilized if needed. The member is a function of the depth of the hole to be drilled by the drifter 10.

A hydraulic rotation motor 24 is mounted on the housing 14. The purpose of the motor 24 is to cause rotation of the shank bar 18, the drill steels 20 and the bit 22 during the drilling of the formation.

The impact mechanism 12 is mounted on a feed mechanism 26.- The feed mechanism is arranged to move the impact mechanism 12 toward and away from the formation to be drilled. A feed motor 28, which is also hydraulically powered, is mounted on the feed mechanism 26 and arranged to cause movement of the impact mechanism 12 in the desired direction.

As previously mentioned, the rotation motor 24is arranged to provide rotation of the bit 22. Power for the rotation motor 24 is derived from a rotation pump 30 that is connected to the rotation motor 24 by a conduit 32. The rotation motor 24 is also connected by a conduit 34 with a hydraulic reservoir 36.

Operably disposed in the conduits 32 and 34 is a three-position valve 38 that, in one position, prevents flow from the pump 30 to the motor 24, and a second position permits flow from the pump 30 to the motor 24 through the conduit 32. When in the second position, fluid returns from the motor 24 through the conduit 34 to the reservoir 36. In the third position of the valve 38, fluid flows from the pump 30 through the line 34 to the motor 24 and returns through the conduit 32 to the reservoir 36. It will be appreciated that the first and third positions of the valve 38 will cause the moto 24 to rotate in opposite directions.

Power to drive the reciprocating piston or striker 16 is derived from an impact pump through a conduit 42 that is connected to a conduit 44. The conduit 44 extends from the pump 40 to the reservoir 36 through a two-position impact valve 46. In the position of the impact valve 46 illustrated, fluid from the pump 40 flows through the valve 46 to the reservoir 36 and thus is not directed through the conduit 42 to the reciprocating piston 16. In the other position of the impact valve 46, the conduit 44 extending to the reservoir 36 is blocked by the valve 46 and, consequently, fluid is directed from the conduit 44 through the conduit 42 to the impact mechanism 12 causing reciprocation of the piston 16.

Power for driving the feed motor 28 is provided by a feed pump 48. The feed pump 48 is connected to a three-position feed valve 50 by a conduit 52. The feed valve 50 is connected to one side of the feed motor 28 by a conduit 54 and to the opposite side of the feed motor 28 by a conduit 56. As can be seen in the drawing, the conduit 54 extends directly from the feed valve 50 to the feed motor 28. A pressure reducing device 58 is disposed in the conduit 56.

The pressure reducing device 58 includes an adjustable pressure responsive reducing mechanism 60 and a bypass 62 that has a check valve 64 located therein. The check valve 64 is arranged to freely permit fluid flow through the bypass 62 as fluid flows through the conduit 56 from the'feed motor 28, but to prevent flow The feed valve 50 is arranged so that in one position fluid will flow through the conduit 52 from the feed pump 48 through the valve 50 directly into the conduit 54 to the feed motor 28. When receiving fluid from the conduit 54, the feed motor 28 rotates in a direction to move the impact mechanism 12 relatively away from the formation to be drilled. As the fluid flows from the conduit 54 through the feed motor 28, it returns through the conduit 56 through the feed valve 50 where it is directed through a conduit 66 to the reservoir 36.

A conduit 68 extends from the conduit 56 between the pressure reducing valve 58 and the feed valve 50 to an intersection with the conduit 42 which leads to the impact mechanism 12. Operably disposed in the conduit 68 is an adjustable, pressure-responsive, bypass valve 70 that is normally closed but that permits the flow of fluid through the conduit 68 to the conduit 42 when the pressure in the feed motor 28 and the conduit 56 exceeds a predetermined and preset value. The

valve 70-is preferably set to open at a pressure slightly higher than the highest expected or desired feed pressurein the conduits 52 and 56.

It will be appreciated from the foregoing that the feed motor 28 drives the impact mechanism 12 and bit 22 into engagement with the formation. The feed motor 28 continues to exert a force thereon until the pressure builds up in the feed motor 28 due to the resistance of the formation until the pressure exceeds the preset,.

predetermined value. At this point, the bypass valve 70 opens permitting excess fluid pressure flowing through the conduit 56 to flow through the conduit 68 into the impact mechanism 12 via, the conduit 42. This addi-' tional fluid flow and pressure increases the power available to the impact mechanism 12 whereby greater efficiency can be obtained in the drilling of the formation.

DESCRIPTION OF THE OPERATION OF THE PREFERRED EMBODIMENT For the purpose of explaining the operation of the hydraulic drifter 10, it is assumed that the drifter is positioned adjacent the formation to be drilled. With the pumps 30, 40 and 48 running, the rotation valve 38 will be moved to the position wherein fluid flows from the pump 30 through the conduit 32 to the rotation motor 24 and returns therefrom through the conduit 34 to the reservoir 36. If it is desired to rotate the bit 22 in the opposite direction, the valve 38 can be repositioned so that the flow will be in the opposite direction through the conduits 32 and 34.

Reciprocation of the piston 16 can be started if desired before the bit 22 is in engagement with the formation to be drilled. Reciprocation of the piston 16 is accomplished by closing the impact valve 46 so that fluid flows from the pump 40 through the conduits 44 and 42 to the impact mechanism 12. A detailed description of the operationof one from of drifter 10 that can be utilized may be found in previously mentioned US. Pat. No. 3,701,386. With the impact mechanism 12 in the up position on the feed mechanism 26, the reciprocating piston 16 will not strike the shank bar 18 because the shank bar 18, drill steels 20 and bit 22 have sufficient weight to retain those members in a position in the housing 14 wherein the bar 18 cannot be engaged by the piston 16.

Movement or traverse of the imp'act'mechanism 12 toward the formation is accomplished by moving the feed valve 50 to the position wherein fluid flow from the feed pump 48 to the feed motor 28 occurs through the conduits 52 and 56. Fluid from the feed motor 28 returns through the conduit 54, the feed valve 50.and the conduit 66 to the reservoir 36. With flow in this direction, the feed motor 28 has the proper rotational direction so that the impact mechanism 12 is moved downwardly, that is, toward the formation to be drilled.

After the drill bit 22 is in engagement with the formation, fluid pressure through the conduit 56 is exerted on the feed motor 28 maintaining a force downwardly to hold the impact mechanism against the formation. During this time, the piston 16 is reciprocating and engaging the striker bar 18 and, thus, exerting an impact force on the drill bit 22. If the drilling is relatively easy, that is if the bit 22 penetrates the formation without undue difficulty, the system continues to operate as described.

If, on the other hand, the formation is extremely difficult to drill, the feed motor 28 continues. to exert a downward force on the impact mechanism 12 but little or no movement of the impact mechanism occurs and, thus, the feed motor 28 approaches stall condition. As this condition is approached, pressure builds upin the feed motor 28 and the conduit 56 until it exceeds the preset pressure of the bypass valve 70. When this occurs, the bypass valve 70 opens permitting flow from the conduit 52 into the conduit 68 which, as previously mentioned, is connected with the conduit 42. It will be appreciated that the feed pump 48 is now supplying fluid under pressure through the conduit 42 to the impact mechanism 12 to augment the fluid being supplied to the impact mechanism 12 by the impact pump 40. Thus, under circumstances where extreme difficulty in drilling is encountered, the system described provides a means for supplying additional power to the impact mechanism 12 to provide a greater rate of formation penetration.

When .it is necessary or desirable to remove the bit 22 from the formation, the feed valve 50 is returned to the position wherein the feed pump 48 supplies fluid to the feed motor 28 through the conduit 54. As this flow occurs, the rotational direction of the feed motor 28 is reversed and the bypass valve 70 closes so that return fluid from the feed motor 28 flows through the conduit 56, the bypass line 62 of the pressure reducing valve 58 and into the reservoir 36 through the conduit 66. Rotation of the feed motor 28 in this direction moves the impact mechanism 12 upwardly or away from the formation to be drilled. The drifter is now returned substantially to its starting position. If desired, the rotation valve, impact valve and feed valve can be move to the closed positions.

From the foregoing, it will be appreciated that the system described provides the maximum volume of hydraulic fluid at the maximum pressure to the reciproeating piston 16 of the impact mechanism 12 at the time when the most force is required in the impact mechanism. The system also provides the feed motor with sufficient volume of fluid to maintain the feed force on the drifter 10 during the maximum difficulty of drilling. The volume and pressure fluid from the pump 48 is automatically diverted when needed and, yet, providing maximum fluid volume to the feed motor 28 when it is desired to move the impact mechanism 12 rapidly along the feed mechanism 26 in either direction.

It will be understood that the foregoing embodiment is presented by way of example only and that many modifications and changes can be made thereto without departing from the spirit or scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In an improved hydraulic circuit for controlling the feed force and impact force exerted by a hydraulic drifter that includes an impact mechanism including a hydraulically-actuated, reciprocating piston for causing the impact force and a feed mechanism powered by a hydraulic motor for moving the impact mechanism toward and away from the formation being drilled, the improvement comprising:

first means for supplying pressure fluid to the impact mechanism; 2 second means for supplying pressure fluid to the feed mechanism; and,

third means interconnecting said first and second means for fluid communication, said third means including normally-closed valve means, presettable to open in response to apredetermined pressure in said second means permitting fluid flow from said second means to said first means when the pressure in said second means exceeds the predetermined pressure, whereby the impact mechanism receives v fluid under pressure from the feed mechanism.

' 2. The hydraulic circuit of claim 1 wherein said second means includes pressure reducing means for limiting the maximum fluid pressure applied to the hydraulic motor. I t

3. The hydraulic circuit of claim 2 wherein said valve means is preset to open at a pressure above maximum pressure in said second means.

4. The hydraulic circuit of claim 2 wherein said second means also includes bypass means providing a fluid flow path around said pressure reducing means, said bypass means having a one-way valve disposed therein permitting flow around said pressure reducing means in one direction and preventing flow around said pressure reducing means in the opposite direction.

5. The hydraulic circuit of claim 4 wherein said oneway valve is oriented to prevent flow through said bypass means when said second means is supplying pressure to the feed mechanism in a direction to cause the feed mechanism to move the impact mechanism toward the formation to be drilled.

6. In an improved hydraulic circuit for controlling the feed force and impact force exerted by a hydraulic drifter that includes an impact mechanism including a hydraulically-actuated, reciprocating piston for causing the impact force and a feed mechanism powered by a hydraulic motor for moving the impact mechanism toward and away from the formation being drilled, the

improvement comprising:

an impact pump connected in fluid communication with the impact mechanism; impact valve means arranged to interrupt the fluid communication between said impact pump and impact mechanism; feed valve means; a feed pump connected in fluid communication with said feed valve means; first and second conduits providing fluid communication between said feed valve means and the hydraulic motor; pressure-reducing valve means located in said second conduit for limiting the fluid pressure in the hydraulic motor to a predetermined value; I a third conduit connecting said second conduit in fluid communication with the impact mechanism; and, pressure-responsive valve means in said third conduit for providing fluid flow through said third conduit to the impact mechanism from said feed pump when the pressure in said second conduit and pressure-reducing valve means exceeds said predetermined value to provide additional fluid power from the feed pump for operation of the impact mechanism when the hydraulic motor of the feed mechanism is at or near stall condition. 7. A method for automatically controlling the application of hydraulic power between the impact force and feed force in a hydraulic drifter that includes an impact mechanism having a hydraulically-actuated, reciprocating piston for causing the impact force; an impact pump for supplying hydraulic fluid to the impact mechanism; a feed mechanism powered by a hydraulic motor for moving the impact mechanism toward and away from the formation being drilled; a feed pump for supplying hydraulic fluid to the feed mechanism; and pressure-responsive valve means operably disposed between said impact mechanism and feed mechanism, the method comprising the steps of:

supplying fluid under pressure to cause reciprocation of the piston in the impact mechanism by means of an impact pump;

supplying fluid to the feed mechanism to force the impact mechanism into engagement with the formation by means of a feed pump; and,

opening the valve means to divert a portion of the pressure fluid from the feed pump and feed mechanism to the impact mechanism through the valve means to increase the power available to the impact mechanism when the pressure in the feed mechanism exceeds a predetermined value.

8. The method of claim 7 wherein the step of diverting a portion of the pressure fluid includes presetting the valve means to open when the hydraulic motor is at or near stall.

9. The method of claim 7 including the step of closing the valve means to prevent the diversion of the pressure fluid when the pressure in the feed mechanism is below the predetermined value. 

1. In an improved hydraulic circuit for controlling the feed force and impact force exerted by a hydraulic drifter that includes an impact mechanism including a hydraulically-actuated, reciprocating piston for causing the impact force and a feed mechanism powered by a hydraulic motor for moving the impact mechanism toward and away from the formation being drilled, the improvement comprising: first means for supplying pressure fluid to the impact mechanism; second means for supplying pressure fluid to the feed mechanism; and, third means interconnecting said first and second means for fluid communication, said third means including normally-closed valve means, presettable to open in response to a predetermined pressure in said second means permitting fluid flow from said second means to said first means when the pressure in said second means exceeds the predetermined pressure, whereby the impact mechanism receives fluid under pressure from the feed mechanism.
 2. The hydraulic circuit of claim 1 wherein said second means includes pressure reducing means for limiting the maximum fluid pressure applied to the hydraulic motor.
 3. The hydraulic circuit of claim 2 wherein said valve means is preset to open at a pressure above maximum prEssure in said second means.
 4. The hydraulic circuit of claim 2 wherein said second means also includes bypass means providing a fluid flow path around said pressure reducing means, said bypass means having a one-way valve disposed therein permitting flow around said pressure reducing means in one direction and preventing flow around said pressure reducing means in the opposite direction.
 5. The hydraulic circuit of claim 4 wherein said one-way valve is oriented to prevent flow through said bypass means when said second means is supplying pressure to the feed mechanism in a direction to cause the feed mechanism to move the impact mechanism toward the formation to be drilled.
 6. In an improved hydraulic circuit for controlling the feed force and impact force exerted by a hydraulic drifter that includes an impact mechanism including a hydraulically-actuated, reciprocating piston for causing the impact force and a feed mechanism powered by a hydraulic motor for moving the impact mechanism toward and away from the formation being drilled, the improvement comprising: an impact pump connected in fluid communication with the impact mechanism; impact valve means arranged to interrupt the fluid communication between said impact pump and impact mechanism; feed valve means; a feed pump connected in fluid communication with said feed valve means; first and second conduits providing fluid communication between said feed valve means and the hydraulic motor; pressure-reducing valve means located in said second conduit for limiting the fluid pressure in the hydraulic motor to a predetermined value; a third conduit connecting said second conduit in fluid communication with the impact mechanism; and, pressure-responsive valve means in said third conduit for providing fluid flow through said third conduit to the impact mechanism from said feed pump when the pressure in said second conduit and pressure-reducing valve means exceeds said predetermined value to provide additional fluid power from the feed pump for operation of the impact mechanism when the hydraulic motor of the feed mechanism is at or near stall condition.
 7. A method for automatically controlling the application of hydraulic power between the impact force and feed force in a hydraulic drifter that includes an impact mechanism having a hydraulically-actuated, reciprocating piston for causing the impact force; an impact pump for supplying hydraulic fluid to the impact mechanism; a feed mechanism powered by a hydraulic motor for moving the impact mechanism toward and away from the formation being drilled; a feed pump for supplying hydraulic fluid to the feed mechanism; and pressure-responsive valve means operably disposed between said impact mechanism and feed mechanism, the method comprising the steps of: supplying fluid under pressure to cause reciprocation of the piston in the impact mechanism by means of an impact pump; supplying fluid to the feed mechanism to force the impact mechanism into engagement with the formation by means of a feed pump; and, opening the valve means to divert a portion of the pressure fluid from the feed pump and feed mechanism to the impact mechanism through the valve means to increase the power available to the impact mechanism when the pressure in the feed mechanism exceeds a predetermined value.
 8. The method of claim 7 wherein the step of diverting a portion of the pressure fluid includes presetting the valve means to open when the hydraulic motor is at or near stall.
 9. The method of claim 7 including the step of closing the valve means to prevent the diversion of the pressure fluid when the pressure in the feed mechanism is below the predetermined value. 